Sliding device for a vehicle seat

ABSTRACT

A sliding device for a vehicle seat is provided. The sliding device includes a pair of parallel slideways, each of which comprises a lower rail, an upper rail slidably mounted to the lower rail and a latch for allowing/preventing a movement of the upper rail relative to the lower rail. A releasing member is provided for driving the latches to a position in which the upper rails are free to move relative to the lower rails. Each latch has a rear portion which is bent into a “U”-like shape and comprises a lower leg carrying latching elements configured to cooperate with corresponding latching elements provided in the lower rail and an upper leg configured to engage the releasing member. The design of the latches improves the reliability of the sliding device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. application Ser. No. 16/615,159, which is a 371 National Stage of International Application No. PCT/IB2019/053167, filed Apr. 17, 2019, which claims the benefit under 35 USC 119 of Italian Application No. 102018000005731, filed May 25, 2018.

TECHNICAL FIELD

The present invention relates to a sliding device for a vehicle seat.

More particularly, the present invention relates to a sliding device for a vehicle seat which guarantees an improved reliability with respect to accidental, undesired sliding of the vehicle seat relative to the vehicle floor.

PRIOR ART

Vehicle seats generally have a sliding function for pushing or pulling the seat cushion in a forward or backward direction, a height adjustment function for adjusting the height of the seat cushion and a reclining function for adjusting the inclination of the seat backrest relative to the seat cushion.

The aforesaid sliding function is generally implemented by a sliding device which comprises a pair of parallel slideways, each of which comprises a lower rail attached to the vehicle floor and an upper rail attached to the vehicle seat, the upper rail being constrained to the lower rail, but being able to slide relative to said lower rail.

Each slideway of the sliding device further comprises a latch for allowing/preventing movement of the upper rail relative to the lower rail. Such latch is normally in a locking position, in which it prevents the upper rail from sliding with respect to the lower rail, thus avoiding accidental displacements of the seat with respect to the vehicle floor. The sliding device is further provided with a releasing member which can be used by a user for moving the latches of the slideways to an unlocking position, in which the upper rail is free to move relative to the lower rail, so that the position of the seat with respect to the vehicle floor can be adjusted. Such releasing member can be made, for instance, as a “U”-shaped handle having two substantially parallel arms, the end portions of which are configured to simultaneously act upon respective latches of the slideways of the sliding device for driving them to their unlocking position.

Such a sliding device is disclosed, for instance, in patent applications EP 752 338, FR 2 969 967 and WO 2014/049238.

However, a sliding device of the kind disclosed in the aforesaid document is not free from drawbacks.

More particularly, the latches of said device shows poor reliability with respect to the engagement both with the respective slideways and with the releasing member, so that they easily become disengaged from said slideways and/or from said releasing member, therefore causing malfunctioning of the sliding device.

Moreover, the latches of said device are designed so that the fulcrum of the releasing member is at the opposite end of the latches with respect to the portion of the latches engaging the lower rails. As a result, even a slight, accidental movement of the releasing member can be sufficient for moving the latches in their unlocking position and allowing the upper rails to slide relative to the lower rails, so that the risk of an accidental, undesired displacement of the vehicle seat relative to the vehicle floor cannot be effectively avoided.

Therefore, the main object of the present invention is to obviate to such drawbacks by providing a sliding device comprising latches having an improved design, allowing to improve the reliability of the sliding device.

This and other objects are achieved by a sliding device as claimed in the appended claims.

SUMMARY

The sliding device of the invention comprises a pair of parallel slideways, each of which comprises a lower rail, an upper rail slidably mounted to said lower rail and a latch for selectively allowing/preventing movement of said upper rail relative to said lower rail, wherein each of the latches is received inside the respective slideway and is arranged between the upper and lower rails; the sliding device of the invention is further provided with a releasing member for simultaneously switching said latches from a locking position in which the movement of the upper rails of the slideways relative to the respective lower rails is prevented, to an unlocking position, in which the movement of the upper rails of the slideways relative to the respective lower rails is allowed, said releasing member being preferably made as a “U”-shaped handle having two substantially parallel arms, the end portions of which are configured to simultaneously act upon respective latches of said slideways.

According to the invention, each of said latches comprises a front portion which is fixed to the respective upper rail and a rear portion which is bent into a “U”-like shape and comprises a lower leg carrying latching elements configured to cooperate with corresponding latching elements provided in the lower rail for locking said upper rail relative to said lower rail, and an upper leg configured to engage the releasing member.

In a preferred embodiment of the invention, said upper leg carries engaging elements for engaging corresponding engaging elements provided in the releasing member.

In a preferred embodiment of the invention, the lower rail has a substantially “U”-like shaped cross-section and comprises a lower wall and two upwardly oriented parallel walls, each of which ends with an inwardly and downwardly bent edge, the latching elements of the lower rail comprise a plurality of downwardly extending teeth which are equally spaced along said edges of said lower rail, and the latching elements of the latch correspondingly comprise a plurality of through-holes, arranged on both sides of the lower leg of the rear portion of the latch and configured to receive respective teeth of said lower rail.

In a preferred embodiment of the invention, the engaging elements of the releasing handle comprise a notch provided at the end portion of each arm of said handle and the engaging elements of each latch correspondingly comprise a window, the edge of which engages the notch of a respective arm of the releasing handle.

According to this preferred embodiment, the end portions of the arms of the release handle are tapered beyond the notches.

In a preferred embodiment of the invention, each latch comprises an intermediate portion between its front portion and its rear portion, which intermediate portion extends in a substantially vertical direction and is provided with an opening for the passage of a respective arm of the releasing handle, the edge of said opening being the fulcrum around which the arms of the releasing handle pivot for moving the latches to their unlocking position when actuated by the user.

In a preferred embodiment of the invention, each latch is fixed to the respective upper rail at two different points, which are aligned and spaced apart from each other in the longitudinal direction of said upper rail, so that rotation of the latch relative to the upper rail is effectively prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become more evident from the detailed description of a preferred embodiment thereof, given by way of non limiting example, with reference to the attached drawing, in which:

FIG. 1 a is a perspective view of a sliding device according to the invention;

FIG. 1 b is an exploded view of the sliding device of FIG. 1 a

FIG. 2 is a cross-sectional view of the sliding device of FIG. 1 a along the line II-II;

FIG. 3 is a perspective view of one of the latches of the sliding device of FIGS. 1 a -1 b;

FIG. 4 shows a detail of the sliding device of FIGS. 1 a-1 b , illustrating the engagement of the releasing handle with the latches.

FIG. 5 is a perspective view of one of the latches of the sliding device of FIGS. 1 a-1 b according to a first variant;

FIG. 6 is a perspective view of one of the latches of the sliding device of FIGS. 1 a-1 b according to a second variant;

FIG. 7 is a perspective of one of the latches of the sliding device of FIGS. 1 a-1 b according to a third variant;

FIG. 8 is a cross-sectional view of the sliding device of FIG. 1 a along the line II-II, incorporating a latch according to the third variant.

DETAILED DESCRIPTION

With reference to FIGS. 1 a and 1 b , a sliding device 1 according to the invention is shown.

In a per se known manner, the sliding device 1 comprises a pair of parallel slideways 3 a, 3 b, each comprising a lower rail 5 a, 5 b, intended to be attached to the vehicle floor (for instance by threaded fasteners 6 a, 6 b), and an upper rail 7 a, 7 b, intended to be attached to the frame of a vehicle seat.

Each upper rail 7 a, 7 b is constrained to the respective lower rail. To this purpose, each lower rail has a cross-section having the shape of an upwardly open “U” and comprises a lower wall 9 a, 9 b and a pair of parallel, upwardly oriented vertical walls 11 a, 11 b, ending with respective inwardly and downwardly bent edges 13 a, 13 b; correspondingly, each upper rail has a cross-section having the shape of a downwardly open “U” and comprises an upper wall 15 a, 15 b and a pair of parallel, downwardly oriented vertical walls 17 a, 17 b, ending with respective outwardly and upwardly bent edges 19 a, 19 b: the outwardly and upwardly bent edges 19 a, 19 b of the upper rails 7 a, 7 b may become engaged under the inwardly and downwardly bent edges 13 a, 13 b of the respective lower rails 5 a, 5 b.

As a result, said upper rails 7 a, 7 b are constrained to the lower rails 5 a, 5 b, but can slide relative to said lower rails.

In order to selectively allow/prevent a relative sliding movement between the upper rails and the lower rails, each slideway 3 a, 3 b is provided with a latch 21 a, 21 b, which is received in the slideway, between the lower rail and the upper rail.

The latches 21 a, 21 b according to the invention are shown in greater detail in FIG. 3 .

Each latch 21 a, 21 b has a front portion 23 a, 23 b and a rear portion 25 a, 25 b, joined by an intermediate portion 27 a, 27, wherein said front portion 23 a, 23 is fixed to the respective upper rail 7 a, 7 b and said rear portion 25 a, 25 b comprises latching elements configured to cooperate with corresponding latching elements provided in the respective lower rail 5 a, 5 b for preventing the upper rails from sliding relative to the lower rails, as will be explained in detail later.

Under normal conditions, the latches 21 a, 21 b are in their locking position, in which they prevent the upper rails from sliding relative to the lower rails.

In order to allow a user to adjust the position of the seat relative to the vehicle floor, the sliding device 1 further comprises a releasing member 29, arranged for driving the latches 21 a, 21 b to an unlocking position, in which they allow the upper rails to slide relative to the lower rails.

The releasing member is made as a “U”-shaped releasing handle 29 comprising a middle gripping portion 29 c and two substantially parallel arms 29 a, 29 b, the end portions of which are arranged to drive the respective latches 21 a, 21 b to their unlocking position, as will be described in detail later.

According to the invention, the rear portion 25 a, 25 b of each latch 21 a, 21 b is bent into a “U” shape and comprises a lower leg 31 a, 31 b and un upper leg 33 a, 33 b, joined by a curved, vertically oriented section 35 a, 35 b.

In the lower leg 31 a, 31 b, latching elements 37 a, 37 b are provided, which are configured to cooperate with corresponding latching elements 41 a, 41 b of the lower rails 5 a, 5 b for locking the upper rails relative to the lower rails.

In the shown embodiment, the latching elements of the lower rails comprise a plurality of downwardly extending teeth 41 a, 41 b provided along the inwardly and downwardly bent edges 11 a, 11 b of the lower rails 5 a, 5 b.

Correspondingly, the lower leg 31 a, 31 b of the rear portion of each latch comprises, on both sides thereof, lateral wings 39 a, 39 b, which extend through openings arranged in vertical walls 17 a, 17 b of the upper rails 7 a, 7 b, and one or more through-holes 37 a, 37 b are provided in each lateral wing, said through-holes 37 a, 37 b being configured to receive respective teeth 41 a, 41 b of the lower rails 5 a, 5 b, thus acting as latching elements of the latch.

In the upper leg 33 a, 33 b, an engaging element 43 a, 43 b is provided, which is configured to cooperate with a corresponding engaging element 45 a, 45 b arranged at the end portion of a respective arm 29 a, 29 b of the releasing handle for achieving the engagement between said releasing handle and the latches.

As can be seen in FIG. 4 , in the shown embodiment, the end portion of each arm 29 a, 29 b of the releasing handle 29 is provided with a notch 45 a, 45 b as engaging element for the engagement with the respective latch.

Correspondingly, the upper leg 33 a, 33 b of the rear portion 25 a, 25 b of each latch is provided with a corresponding window 43 a, 43 b as engaging element, the edge of said window being arranged to become engaged in the corresponding notch 45 a, 45 b.

FIG. 4 also shows that each latch 21 a, 21 b also comprises an intermediate portion 27 a, 27 b, arranged between the front portion 23 a, 23 b and the rear portion 25 a, 25 b, which intermediate portion is substantially vertically oriented and is provided with an opening 47 a, 47 b for the passage of the respective arm 29 a, 29 b of the releasing handle.

As can be seen in FIG. 4 , said arm 29 a, 29 b of the releasing handle is provided with a collar 49 a, 49 b, having a diameter larger than the diameter of the opening 47 a, 47 b, so that the arm cannot project further towards the rear portion of the latch and the notch 45 a, 45 b cannot become disengaged from the edge of the window 43, 43 b.

Always with reference to FIG. 4 , it is to be noted that the end portions of the arms 29 a, 29 b of the releasing handle, beyond the notches 45 a, 45 b, are preferably tapered, so as to make the engagement with the respective latch easier.

With reference now to FIG. 5 , a latch 21 a, 21 b according to a first variant of the latch of FIG. 3 is shown.

Also, according to the variant of FIG. 5 , the latch 21 a, 21 b has a front portion 23 a, 23 b and a rear portion 25 a, 25 b, joined by an intermediate portion 27 a, 27 b, said front portion 23 a, 23 b being intended to be fixed to the respective upper rail 7 a, 7 b and said rear portion 25 a, 25 b being intended to exert a latching effect on the respective lower rail 5 a, 5 b.

Furthermore, also according to the variant of FIG. 5 , the rear portion 25 a, 25 b of each latch 21 a, 21 b is bent into a “U” shape and comprises a lower leg 31 a, 31 b and un upper leg 33 a, 33 b, joined by a curved, vertically oriented section 35 a, 35 b, said lower leg 31 a, 31 b carrying latching elements 37 a, 37 b configured to cooperate with corresponding latching elements of the lower rails and said upper leg 33 a, 33 b being intended to engage the end portion of a respective arm of the releasing handle 29.

The latch 21 a, 21 b of FIG. 5 differs from the latch shown in FIG. 3 in that the lower leg 31 a, 31 b comprises a prolongation 55 a, 55 b extending towards the intermediate portion 27 a, 27 b and an upwardly projecting rib 57 a, 57 b is provided on said prolongation 55 a, 55 b.

The upwardly projecting rib 57 a, 57 b is arranged to penetrate into a corresponding groove provided in the bottom surface of the corresponding arm 29 a, 29 b of the releasing handle 29. Said upwardly projecting rib 57 a, 57 b allows to ensure a positive engagement between the latch 21 a, 21 b and the corresponding arm of the releasing handle.

Thanks to the provision of the upwardly projecting rib 57 a, 57 b, the coupling between the lower surface of the upper leg 33 a, 33 b of the latch 21 a, 21 b and the upper surface of the corresponding arm of the releasing handle can be sufficient for obtaining the engagement between said latch and said arm of said releasing handle.

As can be seen in FIG. 5 , the upwardly projecting rib 57 a, 57 b preferably has a tapered shape, the height of said rib increasing going from the intermediate portion 27 a, 27 b of the latch towards the rear portion thereof. This tapered shape allows to obtain a progressively positive engagement between the latch 21 a, 21 b and the corresponding arm of the releasing handle.

With reference now to FIG. 6 , a latch 21 a, 21 b according to a second variant of the latch of FIG. 3 is shown.

Also, according to the variant of FIG. 6 , the latch 21 a, 21 b has a front portion 23 a, 23 b and a rear portion 25 a, 25 b, joined by an intermediate portion 27 a, 27 b, said front portion 23 a, 23 b being intended to be fixed to the respective upper rail 7 a, 7 b and said rear portion 25 a, 25 b being intended to exert a latching effect on the respective lower rail 5 a, 5 b.

Furthermore, also according to the variant of FIG. 6 , the rear portion 25 a, 25 b of each latch 21 a, 21 b is bent into a “U” shape and comprises a lower leg 31 a, 31 b and un upper leg 33 a, 33 b, joined by a curved, vertically oriented section 35 a, 35 b, said lower leg 31 a, 31 b carrying latching elements 37 a, 37 b configured to cooperate with corresponding latching elements of the lower rails and said upper leg 33 a, 33 b being intended to engage the end portion of a respective arm of the releasing handle 29.

The latch 21 a, 21 b of FIG. 6 differs from the latch shown in FIG. 3 in that the curved, vertically oriented section 35 a, 35 b of the rear portion of the latch is provided with two parallel slits defining two side portions 59 a, 59 b joining the lower and upper legs of the rear portion of the latch and a middle portion 61 a, 61 b extending in a substantially vertical direction and ending with a rearwardly bent free end 63 a, 63 b.

The rearwardly bent free end 63 a, 63 b of said middle portion is configured to protrude through the corresponding upper rail 7 a, 7 b and can be advantageously used for adjusting the upper and lower rails relative to each other before assembly of the releasing handle.

This arrangement provides for an improved flexibility in the assembly sequence and reduces the complexity of said assembly sequence.

Referring again to FIG. 3 , as mentioned above, each latch 21 a, 21 b has a front portion 23 a, 23 b, which is fixed to the respective upper rail 7 a, 7 b.

As can be seen in FIG. 3 , said front portion 23 a, 23 b may be provided with at least two bosses 51 a, 51 b which are aligned along the longitudinal axes of the upper rails and are spaced apart from each other along the direction of said longitudinal axes.

Said bosses are configured to protrude through corresponding holes provided in the upper wall 15 a, 15 b of the corresponding “U”-shaped upper rail 7 a, 7 b.

Thanks to the presence of said aligned and spaced apart bosses 51 a, 51 b, any relative rotation between the latch and the corresponding upper rail can be prevented.

The latches 21 a, 21 b may be fixed to the upper rails also at their intermediate portions 27 a, 27 b.

As shown in FIG. 3 , the walls of said intermediate portions 27 a, 27 b have a shaped profile comprising indentations 53 a, 53 b, through which a positive lock with the lateral walls 17 a, 17 b of the “U”-shaped upper rail 7 a, 7 b can be obtained.

With reference now to FIG. 7 , a latch 21 a, 21 b according to a third variant of the latch of FIG. 3 is shown.

Also, according to the variant of FIG. 7 , the latch 21 a, 21 b has a front portion 23 a, 23 b and a rear portion 25 a, 25 b, joined by an intermediate portion 27 a, 27 b, said front portion 23 a, 23 b being intended to be fixed to the respective upper rail 7 a, 7 b and said rear portion 25 a, 25 b being intended to exert a latching effect on the respective lower rail 5 a, 5 b.

Furthermore, also according to the variant of FIG. 7 , the rear portion 25 a, 25 b of each latch 21 a, 21 b is bent into a “U” shape and comprises a lower leg 31 a, 31 b and un upper leg 33 a, 33 b, joined by a curved, vertically oriented section 35 a, 35 b, said lower leg 31 a, 31 b carrying latching elements 37 a, 37 b configured to cooperate with corresponding latching elements of the lower rails and said upper leg 33 a, 33 b being intended to engage the end portion of a respective arm of the releasing handle 29.

First of all, the latch 21 a, 21 b of FIG. 7 differs from the latch shown in FIG. 3 in that a dome-shaped, upwardly oriented projection 65 a, 65 b is provided on the lower leg 31 a, 31 b of the rear portion of the latch, at the longitudinal axis of said lower leg or close to such longitudinal axis.

Thanks to the provision of such dome-shaped projection 65 a, 65 b, the lower leg of the latch will always contact the corresponding arm of the releasing member at the position of said dome-shaped projection (see also FIG. 8 ). Accordingly, the transmission of forces between the latch and the releasing member will also occur at said dome-shaped projection, with little or no contribution from the other surrounding surfaces.

Advantageously, as the point at which forces are transmitted is fixed and known, the design of the latch 21 a, 21 b according to this third variants helps to achieve a consistent release effort of the releasing member.

Secondly, the latch 21 a, 21 b of FIG. 7 differs from the latch shown in FIG. 3 in that an outwardly extending safety tab 67 a, 67 b is provided on either sides of the intermediate portion 27 a, 27 b of the latch 21 a, 21 b.

Each of said safety tabs 67 a, 67 b engages a corresponding slot 69 a, 69 b provided in the upper rail (see FIG. 8 ).

Thanks to the engagement of the safety tabs 67 a, 67 b in the corresponding slots 69 a, 69 b, it is possible to prevent the rear portion of the latch from excessively moving downwards when a high load is applied. Therefore, the rear portion of the latch is prevented from hitting the lower rail in case of high loads.

Moreover, the engagement of the safety tabs 67 a, 67 b in the corresponding slots 69 a, 69 b helps in correctly guiding the movement rear portion of the latch in the up-down direction, thus avoiding misalignments.

Thirdly, the latch 21 a, 21 b of FIG. 7 differs from the latch shown in FIG. 3 in that the intermediate portion 27 a, 27 b and the rear portion 25 a, 25 b of the latch 21 a, 21 b are not aligned to each other, i.e., they do not lie on the same plane.

This configuration helps to improve the strength of the locking system as the intermediate portion 27 a, 27 b and the rear portion 25 a, 25 b of the latch 21 a, 21 b can be inclined relative to each other in such a way that said rear portion of said latch is as close as possible to be parallel to the lower rail (i.e., horizontal), which improves the engagement between the latching elements of the upper and lower rails, thus allowing to achieve a stronger locking effect.

Furthermore, the latch 21 a, 21 b of FIG. 7 , too, includes means for preventing any relative rotation between the latch and the corresponding upper rail, as in the latch shown in FIG. 3 .

However, in this variant the anti-rotation bosses provided in the latch of FIG. 3 are replaced by a hook 71 a, 71 b upwardly projecting from the front portion 23 a, 23 b of the latch 21 a, 21 b. Such hook 71 a, 71 b is intended to engage a corresponding cutout 73 a, 73 b in the corresponding upper rail (see FIG. 8 ).

The operation of the sliding device 1 according to the invention will be briefly disclosed with reference to FIG. 2 .

The latches 21 a, 21 b are shaped in such a way that when they are in a rest condition, i.e., in the absence of any stresses acting on them, the latching elements (i.e., the through-holes 37 a, 37 b) on their rear portion 25 a, 25 b engage the respective latching elements (i.e., the teeth 41 a, 41 b) of the lower rails 5 a, 5 b, thus locking the upper rails relative to the lower rails.

With the latches in this locking position, the displacement of the upper rails 7 a, 7 b relative to the lower rails 5 a, 5 b of the slideways 3 a, 3 b is effectively prevented.

In order to adjust the position of the vehicle seat relative to the vehicle floor, the latches 21 a, 21 b can be driven to the unlocking position by pulling the gripping portion 29 c of the releasing handle 29 upwardly (see arrow F1 in FIG. 2 ).

As a consequence, the arms 29 a, 29 b of the releasing handle will rotate, the edge of the opening 47 a, 47 b in the intermediate portion 27 a, 27 b of the latches serving as fulcrum for such rotation (see arrow F2 in FIG. 2 ).

As a result of such rotation, the end portions of the arms 29 a, 29 b of the releasing handle 29 will pull the rear portions 25 a, 25 b of the latches 21 a, 21 b downwardly, thus disengaging the latching elements (i.e., the through-holes 37 a, 37 b) of said latches from the respective latching elements (i.e., the teeth 41 a, 41 b) of the lower rails and allowing the upper rails to be displaced relative to the lower rails.

Once the user releases the gripping portion 29 c of the handle 29, the latches 21 a, 21 b return to their rest position, in which they lock the upper rails 7 a, 7 b relative to the lower rails 5 a, 5 b in the new set position.

From the above disclosure, the advantages of the invention will be evident.

The shape of the rear portion of the latches allows to provide a firm engagement between the upper leg of said rear portion of said latches and the end portion of the arms of the releasing handle.

The axial displacement of the arms of the handle relative to the latches is prevented both by the engagement with the engaging elements provided at the rear portion of the latches and by the provision on said arms of the collars with a diameter larger than the diameter of the opening in the intermediate portion of said latches.

By providing the latching elements in the rear portion of the latches in the form of through-holes, a very firm engagement with the latching elements of the lower rails against displacement in any direction can be obtained.

Due to the fact that the arms of the releasing handle pivot about the intermediate portions of latches (i.e., closer to the rear portion of said latches when compared to prior art solutions), slight, accidental movements of the releasing handle are not sufficient for causing an undesired disengagement of the latching elements of the latches from the latching elements of the lower rails.

The above description of a preferred embodiment of the invention has been given merely by way of example and several variants and modifications within the reach of the person skilled in the art can be envisaged, without departing from the scope of the invention as defined by the appended claims.

More particularly, it will be evident to the person skilled in the art that individual features of the different variants of the latch of the sliding device according to the invention shown in the present disclosure could be associated to each other according to any possible combination, thus resulting in new, advantageous variants of the invention. 

The invention claimed is:
 1. A sliding device for a vehicle seat, which sliding device comprises a pair of parallel slideways, each comprising a lower rail, an upper rail, that is slidably mounted to the lower rail, and a latch, which is arranged between the lower rail and the upper rail and selectively allows/prevents movement of the upper rail relative to the lower rail, wherein in a rest condition the latches of both parallel slideways are in a locking position, in which they prevent the movement of the upper rails relative to the lower rails, and wherein the sliding device comprises a releasing member for driving the latches to an unlocking position in which they allow the movement of the upper rails relative to the lower rails, wherein the releasing member is made as a “U”-shaped releasing handle comprising a middle gripping portion and two substantially parallel arms, wherein each of the latches comprises a front portion and a rear portion joined by an intermediate portion, wherein the front portion of each latch is fixed to a respective one of the upper rails and the rear portion of each latch is bent into a “U” shape comprising a lower leg and un upper leg, joined by a curved, vertically oriented section, wherein latching elements configured to cooperate with corresponding latching elements provided in respective lower rails are provided in the lower legs of the rear portions of the latches, and wherein the lower legs of the rear portions of the latches comprise a prolongation extending towards the intermediate portions of the latches and carrying an upwardly projecting rib and wherein the bottom surfaces of the arms of the releasing handle are provided with a groove into which the upwardly projecting rib of a respective one of the latches is arranged to penetrate.
 2. The sliding device according to claim 1, wherein the upwardly projecting ribs have a tapered shape, the height of the ribs increasing going from the intermediate portion towards the rear portion of the latches.
 3. The sliding device according to claim 1, wherein the curved, vertically oriented sections of the rear portions of the latches are provided with two parallel slits defining two side portions joining the lower and upper legs of the rear portions of the latches and a middle portion extending in a substantially vertical direction and ending with a rearwardly bent free end, which is configured to protrude through the upper rails.
 4. The sliding device according to claim 1, wherein each of the lower rails has cross-section having the shape of an upwardly open “U” and comprises a lower wall and a pair of parallel, upwardly oriented vertical walls, ending with respective inwardly and downwardly bent edges, and each of the upper rails has a cross-section having the shape of a downwardly open “U” and comprises an upper wall and a pair of parallel, downwardly oriented vertical walls, ending with respective outwardly and upwardly bent edges, the outwardly and upwardly bent edges of the upper rails being engaged under the inwardly and downwardly bent edges of the lower rails.
 5. The sliding device according to claim 4, wherein the latching elements provided in the lower rails comprise a plurality of downwardly extending teeth provided along the inwardly and downwardly bent edges and the latching elements of the latches comprise a plurality of through-holes arranged in lateral wings extending on both sides of the lower leg of the rear portion of each latch.
 6. The sliding device according to claim 1, wherein the intermediate portion of each latch includes a substantially vertically oriented section that is provided with an opening for the passage of one of the arms of the releasing handle, an edge of each of the openings of the intermediate portions of the latches serving as fulcrum for the rotation of one of the arms of the releasing handle.
 7. The sliding device according to claim 1, wherein each of the upper rails has a longitudinal axis and wherein the front portions of the latches are provided with at least two bosses that are aligned along the longitudinal axes of the upper rails and are spaced apart from each other along the direction of the longitudinal axes, the bosses being received in holes provided in the upper rails.
 8. The sliding device according to claim 1, wherein the intermediate portion of each of the latches has a shaped profile comprising indentations for positive locking to a respective one of the upper rails.
 9. The sliding device according to claim 8, wherein each aim of the releasing handle comprises a collar having a diameter larger than a diameter of openings in the intermediate portions of the latches.
 10. The sliding device according to claim 1, wherein a dome-shaped, upwardly oriented projection is provided on the lower leg of the rear portion of each of the latches, at a longitudinal axis of the lower leg or close to a longitudinal axis of the lower leg.
 11. The sliding device according to claim 1, wherein an outwardly extending safety tab is provided on either sides of the intermediate portion of each of the latches, each of the safety tabs being received in and engaging a slot provided in a respective one of the upper rails.
 12. The sliding device according to claim 1, wherein the intermediate portions of the latches are inclined with respect to the rear portions of the latches.
 13. The sliding device according to claim 1, wherein the front portion of each of the latches is provided with an upwardly projecting hook, the hook being received in a cutout provided in a respective on of the upper rails. 